Batteries on a yacht – what is it like with electricity?

Offshore yachts are equipped with several devices and instruments that are powered by electricity. Throughout the voyage we must take care to ensure that it does not run out. Otherwise, problems can arise, which is something everyone prefers to avoid. The batteries on a yacht are the main source of power and it is good to have a basic knowledge of them.

What batteries are installed on the yacht?

A service pack (powers all instruments and equipment, lighting, etc.) and an independent starter battery. Why is this? For safety. If for some reason (our mistake or failure), we can always start the engine. 


Several factors contribute to how long the batteries last: 

Number and size of batteries: Here, everything will depend on the type of vessel. It is assumed that the larger the yacht, the more batteries. Firstly because physically more of them will fit. Secondly, on larger yachts, there is more equipment that these batteries need to power.  

Age of batteries: Over time, batteries lose their properties. Everyone owns a mobile phone and knows that a new one lasts longer, an old one shorter. In addition, badly used batteries reduce their capacity faster. Therefore, we should take care that the voltage on them never drops too low – this is very damaging to them. 

The number and type of devices they power: On smaller and older vessels you will encounter basic equipment, e.g. fridge, navigational instruments, bilge pump, autopilot. The larger and more modern the yacht, the more amenities (e.g. TV, freezer, larger and more fridges, chart plotter with large colour screen, etc.) and thus even more power requirements. 

How do you charge a batteries on a yacht?

There are two most common ways. The best and most efficient is to connect the yacht to 220V electricity in the marina. This is when the best effect is achieved. Connecting the yacht is the first thing to do after docking and disconnecting is the last. In addition, the batteries can be charged using the motor. Even when we have been sailing for a long time, we can start the engine and the alternator will take care of the rest 🙂 .


Sometimes yachts are equipped with solar panels. True, they will improve the energy balance on the yacht, but let’s not overestimate their effectiveness. They can produce electricity to power a fridge, for example, on an ongoing basis, but to operate the autopilot they may not be enough.  

On larger and better-equipped yachts we may come across a power generator, an independent internal combustion engine that produces 220V. This not only charges our batteries, but can also power the air conditioning, the coffee machine, or, for example, the kettle. The disadvantage here is that alongside the electricity it generates noise. 

What should you bear in mind?

  1. When taking over the yacht, ask what condition the batteries are in. 
  2. Take care not to switch on anything unnecessary. 
  3. Avoid constantly using autopilot when you are sailing all day.  
  4. If possible, do not sail with a “warm fridge”, i.e. one that you have recently filled with products. If you must, sail the first hours with the engine running. 
  5. Use the anchor windlass only with the engine running. 
  6. Regularly check the voltage level on the batteries. Before going to bed, after waking up, and several times during the day, even involuntarily passing by the navigation table where the indicator is located. If the voltage starts to drop start charging the batteries.
  7. Well-used batteries should last 4-6 years. If you over-discharged them and then charged them you may not notice the difference, but a little later you may find you need to replace them much sooner.

With sailing greetings
Grzegorz from

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